Soil lamellae are wonderful and striking features that form from a variety of processes.
They are typically seen in sandy, young soils or sediments.
The most frequent mode of formation is the downward movement of small clay particles and/or iron oxides. Lamellae form as percolating soil-water carries small amounts of clay down a sandy soil profile .
From Mike Badzmierowski, Virginia Tech:
“Water infiltrating the soil will work its way down following the least resistive pathways. The boundary between soil that has been wetted and the unchanged soil is known as the wetting front. If the clay in suspension is near the edge of the wetting front, the clay will be deposited in a contorted initial lamella.” This deposited lamella may act as a filter for future wetting fronts, depositing clay particles and thickening in a snowball-type effect, but flattened into a layer instead of a ball or nodule.
The presence of lamellae in eolian and fluvial sediment deposits indicates marine sediments that are exposed to subaerial pedogenic conditions can turn a marine sediment into a poorly developed, sandy, young soil – fairly rapidly. With continued clay and iron oxide transport into into lamellae layers over hundreds of years, a weakly-developed illuvial B – horizon is able to form (see picture below).
If you ever see soil lamellae when it is raining, get excited, because you are seeing soil forming in front of you eyes!